The present invention relates to a liquid crystal apparatus with a leak current preventing function. In particular, a first invention relates to a liquid crystal apparatus which prevents leak current flowing in a dummy electrode, in a liquid crystal apparatus which has the dummy electrode in order to make uniform a gap between upper and lower transparent substrates in which a liquid crystal layer is inserted therebetween. Further, a second invention relates to a liquid crystal apparatus which prevents leak current flowing in a light-cutting film, in a liquid crystal apparatus in which the light-cutting film is provided on a transparent substrate in order to cut off unnecessary light provided in a liquid crystal unit.
The liquid crystal apparatus with the leak current preventing function according to the present invention is advantageously applied to various products using the liquid crystal apparatus, for example, a liquid television receiver, a liquid crystal monitor, a liquid crystal projector, a liquid crystal view finder, a liquid crystal shutter, a liquid crystal printer, etc.
First, the background of the first invention will be explained below.
In a liquid crystal apparatus, unevenness of brightness occurs on a screen if a thickness of the liquid crystal layer, which is inserted between at least a pair of upper and lower transparent substrates, is not provided uniformly on the whole of the screen. Usually, the thickness of the liquid crystal layer (that is, a gap between the upper and lower transparent substrates) is determined based on the thickness of a ring-like sealing member, which is provided between the upper and lower transparent substrates for sealing the liquid crystal, and based on a diameter of a spacer.
When obtaining a predetermined gap between the transparent substrates by adjusting the thickness of the sealing member and the diameter of the spacer, in the case that the thickness of a transparent electrode film which is formed on each upper and lower transparent substrates cannot be ignored compared to the thickness of the liquid crystal layer, color appearance is changed in accordance with presence or absence of the transparent electrodes at both sides of the upper and lower transparent substrates, so that unevenness of color occurs on the image. As countermeasure to the above unevenness of color, a dummy electrode having the same film thickness as a drive electrode (i.e., one transparent electrode) and being not used for driving the liquid crystal is provided between the upper and lower transparent substrates in order to adjust the gap therebetween.
Further, in accordance with miniaturization of the liquid apparatus, there is a case that the drive electrode must be provided under the sealing member, depending on a relationship on the wiring space, as well as the above case, the dummy electrode also must be provided under the sealing member in order to make uniform the gap between the upper and lower transparent substrates. Further, when a width of the dummy electrode is set to a value larger than that of the drive electrode, the dummy electrode is provided across a plurality of drive electrodes. In this case, as mentioned below, since the drive electrode is short-circuited to the drive electrode of the upper transparent substrate through the dummy electrode, the width and shape of the dummy electrode are the same as that of the drive electrode so that the dummy electrode is arranged face-to-face with the drive electrode.
In this case, however, leak current flows on the dummy electrode which is arranged in the above-mentioned configuration. This is because, as explained in detail below, in the manufacturing process of the liquid crystal apparatus, when contacting the upper and lower transparent substrates with pressure, an insulating film is broken by conductive particles so that the drive electrode and the dummy electrode are short-circuited and the leak current flows on the dummy electrode. As a result, difference occurs on voltage supplied to liquid elements corresponding to the dummy electrode due to the leak current so that unevenness of color or brightness of the image occurs on the surface of the screen.
Next, the background of the second invention will be explained below.
In the above-mentioned liquid crystal apparatus, an image area having one or more liquid crystal elements is formed on the liquid crystal layer inside of the sealing member between the upper and lower transparent substrates, and the light transmission of the liquid crystal is controlled on the image area by controlling the supply voltage between the upper and lower transparent electrodes. In this case, the image brightness of each liquid element is set based on the data so that characters and image are formed on the image area. In this configuration, the light is always transmitted through the gap between the liquid crystal elements and through peripheral portions so that the image on the liquid crystal elements becomes unclear. Accordingly, a light-cutting means is provided to the gap and to peripheral portions in order to cut off unnecessary light as already known in the conventional liquid crystal apparatus.
As a first aspect of the liquid crystal apparatus having the above light-cutting means, there is a known means. That is, the image area, which is arranged inside the sealing member and between the liquid crystal elements, and the peripheral portions in the vicinity of the liquid crystal elements, are cut off by the light-cutting means which are provided to one of upper and lower transparent substrates. Further, the peripheral portions of the image area, which are arranged inside the sealing member apart from the liquid crystal elements, are cut off by a partition means which is called a xe2x80x9cmikiribanxe2x80x9d and is mounted to a holder which supports the upper and lower transparent substrates.
Further, as a means for solving the above-mentioned problems, a second aspect of the liquid crystal apparatus having the following light-cutting means has been known. That is, a light-cutting film is arranged between the liquid crystal elements and in the peripheral area surrounding the image area on at least one of upper and lower transparent substrates. In this case, it may be possible not to use a xe2x80x9cmikiribanxe2x80x9d.
In the above second aspect, however, dust and waterdrops become attached between a leading portion of a signal electrode consisting of an ITO film and a light-cutting film consisting of a Cr film, and the signal electrode is short-circuited to the light-cutting film so that the leak current flows therebetween. As a result, an accident in which the signal electrode is short-circuited to the common electrode occurs. When the leak current occurs due to short-circuit, as mentioned above, it is impossible to display the image on the areas relevant to the liquid crystal elements between these electrodes. Accordingly, in order to avoid the leak current due to short-circuit between these electrodes, there is a structure formed so as not to project the light-cutting film from the sealing member to avoid dust and waterdrops. However, a sufficient effect cannot be obtained in the above mentioned countermeasure.
Accordingly, based on the above-mentioned background, the object of the first invention is to prevent the leak current flowing in the dummy electrode in the liquid crystal apparatus including the dummy electrode.
In order to achieve the above object, according to the first invention, the liquid crystal apparatus with the leak current preventing function includes; a first and second transparent substrates arranged opposite to each other; a first and second transparent electrodes, for an image, both formed opposite inner surfaces of the first and second transparent substrates; a sealing member forming the gap for sealing the liquid crystal and for arranging the liquid crystal injecting area between the first and second transparent substrates; a plurality of conductive particles included dispersedly within the sealing member; non-pixel electrodes which are formed on the position covered by the sealing member for the first and second transparent electrodes; and dummy electrodes formed opposite to the non-image electrodes on the position in which the first and second transparent substrates are covered by the sealing member; wherein the dummy electrode is divided by a plurality of slits.
Further, based on the above-mentioned background, the object of the second invention is to prevent the leak current flowing in the light-cutting film in the liquid crystal apparatus including the light-cutting film.
In order to achieve the above object, according to the second invention, the liquid crystal apparatus with the leak current preventing function includes; first and second transparent substrates arranged opposite to each other; first and second transparent electrodes for image both formed opposite inner surfaces of the first and second transparent substrates; a sealing member forming the gap for sealing the liquid crystal and for arranging the liquid crystal injecting area between the first and second transparent substrates; and a conductive light-cutting film provided at least one inner surface of the first and second transparent substrates for cutting off the unnecessary light in the image area and peripheral area; wherein the light-cutting film is provided at least in portions overlapped to the sealing member and in the vicinity of that portions, and divided into a plurality of sub light-cutting films by the slits.